We Have Calculated a 95% Confidence Interval and Would Like $z ^ { * }$

We have calculated a 95% confidence interval and would like our next
Confidence interval to have a smaller margin of error without losing any
Confidence. In order to do this, we can I. change the $z ^ { * }$ value to a smaller number.
II. take a larger sample.
III. take a smaller sample.

A) I only
B) II only
C) III only
D) I and II
E) I and III